What is The Kingdom of God?

This is not a simple answer as many say it’s for the future only which is false! The Kingdom is not fully here yet, however. Romans chapter 13 tells us to be subject to earthly government authorities. Christ’s authority is not fully established in this world. There still are sinners until HE returns to enforce righteousness! Verse 33 is speaking to the heathen not keeping His commandments.

Matthew 6:33  But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you.
Mat 6:34  Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. Sufficient unto the day is the evil thereof.

The kingdom of God was always a reality in that God has always ruled over all and being right with Him always involved repenting of going your own way and submitting to His reign- and that submission was always expressed by obeying His commandments and keeping the covenant He had established at that time. 
 
Yet what made the kingdom of God as it’s revealed in the New Covenant special in terms of the expectation of the godly Jews who sought godliness ahead of earthly blessings was the Holy Spirit being poured out and dwelling in the hearts of His true people.  This is called being a partaker of the divine nature in 2 Peter 1:4, and it was something the faithful before Pentecost couldn’t have in terms of the Spirit indwelling the deepest part of their being (the heart/spirit) and remaining with them.  I believe this limitation prior to the new Covenant was symbolized by how the Holiest Place, the Holy of Holies in the Tabernacle/Temple was off limits to the people.  So there was something about Christ actually accomplishing the atonement on the cross, rising again, and being seated at the Father’s right hand which made it legal and possible for the Spirit to be poured out to dwell in the hearts of true believers and make them partakers of the divine nature.  This is seen in the following verses:
 
37 In the last day, that great day of the feast, Jesus stood and cried, saying, If any man thirst, let him come unto me, and drink.38 He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water. 39 (But this spake he of the Spirit, which they that believe on him should receive: for the Holy Ghost was not yet given; because that Jesus was not yet glorified.)” (John 7:37-39)
 
32 This Jesus hath God raised up, whereof we all are witnesses.33 Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear. 34 For David is not ascended into the heavens: but he saith himself, The Lord said unto my Lord, Sit thou on my right hand. 35 Until I make thy foes thy footstool. 36 Therefore let all the house of Israel know assuredly, that God hath made the same Jesus, whom ye have crucified, both Lord and Christ. 37 Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do? 38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.39 For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.” (Acts 2:32-39)
 
30 The God of our fathers raised up Jesus, whom ye slew and hanged on a tree.31 Him hath God exalted with his right hand to be a Prince and a Saviour, for to give repentance to Israel, and forgiveness of sins.32 And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him.” (Acts 5:30-32)
 
17 For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.18 For he that in these things serveth Christ is acceptable to God, and approved of men.” (Romans 14:17-18)
 
Now some go wrong in that they teach that the kingdom is fully here.  There is yet a future aspect of the kingdom where Christ will come back in glory and assert His reign over the nations.  Those who are His faithful servants in receiving His reign and partaking in His sufferings here and now will reign with Him then- while those who are rebellious to His reign now will be damned as His conquered enemies then (or be damned eventually at a future time at least– see Revelation 2:26-27, Revelation 11:15-19, 2 Timothy 4:1, Romans 8:17-24, 1 Corinthians 15:24-28, Luke 19:11-27, etc). 
 
This means then what is stated about earthly governments in this present time in Romans chapter 13- God has appointed earthly governments to govern the nations in the meantime and He requires submission to them.  Secular Governments are not inherently anti-Christ as some teach.  They are God-ordained and they should be obeyed  and cooperated with in everything that doesn’t require disobeying God’s Word otherwise.  This explains why the Apostles had no hesitation baptizing soldiers, deputies, jailers, etc in the Book of Acts without making them step down from their government office and their enforcing of the law in a secular capacity.  God’s kingdom is not opposed to law and order being kept in this present world; and when people teach that Christ’s kingdom is inherently opposed to these it is a great error and a great stumbling-block.  This is why the concept of pacifism greatly misrepresents Christ and His kingdom.  It also does much to set up those who adopt it to align with anarchists, hippies, revolutionaries, and other miscreants who need to be rebuked rather than encouraged and/or sympathized with (2 Corinthians 6:14-18).
 
The Kingdom of God

(PRESENT AND FUTURE KINGDOM)
Daniel 2:44  And in the days of these kings shall the God of heaven set up a kingdom, which shall never be destroyed: and the kingdom shall not be left to other people, but it shall break in pieces and consume all these kingdoms, and it shall stand for ever.
Dan 2:45  Forasmuch as thou sawest that the stone was cut out of the mountain without hands, and that it brake in pieces the iron, the brass, the clay, the silver, and the gold; the great God hath made known to the king what shall come to pass hereafter: and the dream is certain, and the interpretation thereof sure.

(NOW ON EARTH) Psa 2:1  Why do the heathen rage, and the people imagine a vain thing?
Psa 2:2  The kings of the earth set themselves, and the rulers take counsel together, against the LORD, and against his anointed, saying,  (Act Chapter 4)
Psa 2:3  Let us break their bands asunder, and cast away their cords from us.
Psa 2:4  He that sitteth in the heavens shall laugh: the Lord shall have them in derision.
Psa 2:5  Then shall he speak unto them in his wrath, and vex them in his sore displeasure.
Psa 2:6  Yet have I set my king upon my holy hill of Zion.
Psa 2:7  I will declare the decree: the LORD hath said unto me, Thou art my Son; this day have I begotten thee.
Psa 2:8  Ask of me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession.

(FUTURE KINGDOM) Psa 2:9  Thou shalt break them with a rod of iron; thou shalt dash them in pieces like a potter’s vessel.

(GOSPEL PRESENTATION) Psa 2:10  Be wise now therefore, O ye kings: be instructed, ye judges of the earth.
Psa 2:11  Serve the LORD with fear, and rejoice with trembling.
Psa 2:12  Kiss the Son, lest he be angry, and ye perish from the way, when his wrath is kindled but a little. Blessed are all they that put their trust in him.

Luk 1:31  And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS.
Luk 1:32  He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David:
Luk 1:33  And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end.

Mar 1:14  Now after that John was put in prison, Jesus came into Galilee, preaching the gospel of the kingdom of God,
Mar 1:15  And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.

Rom 14:17  For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.

Mat 19:23  Then said Jesus unto his disciples, Verily I say unto you, That a rich man shall hardly enter into the kingdom of heaven.
Mat 19:24  And again I say unto you, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God.

(FUTURE) Mar 8:34  And when he had called the people unto him with his disciples also, he said unto them, Whosoever will come after me, let him deny himself, and take up his cross, and follow me.
Mar 8:35  For whosoever will save his life shall lose it; but whosoever shall lose his life for my sake and the gospel’s, the same shall save it.
Mar 8:36  For what shall it profit a man, if he shall gain the whole world, and lose his own soul?
Mar 8:37  Or what shall a man give in exchange for his soul?
Mar 8:38  Whosoever therefore shall be ashamed of me and of my words in this adulterous and sinful generation; of him also shall the Son of man be ashamed, when he cometh in the glory of his Father with the holy angels.

Mar 9:1  And he said unto them, Verily I say unto you, That there be some of them that stand here, which shall not taste of death, till they have seen the kingdom of God come with power.

1Co 4:20  For the kingdom of God is not in word, but in power.

Act 2:1  And when the day of Pentecost was fully come, they were all with one accord in one place.
Act 2:2  And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting.
Act 2:3  And there appeared unto them cloven tongues like as of fire, and it sat upon each of them.

Act 2:30  Therefore being a prophet, and knowing that God had sworn with an oath to him, that of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne;
Act 2:31  He seeing this before spake of the resurrection of Christ, that his soul was not left in hell, neither his flesh did see corruption.
Act 2:32  This Jesus hath God raised up, whereof we all are witnesses.
Act 2:33  Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear.
(direct reference to Psalm 2) Act 2:34  For David is not ascended into the heavens: but he saith himself, The LORD said unto my Lord, Sit thou on my right hand,
Act 2:35  Until I make thy foes thy footstool.
Act 2:36  Therefore let all the house of Israel know assuredly, that God hath made that same Jesus, whom ye have crucified, both Lord and Christ.
Act 2:37  Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?
Act 2:38  Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
Act 2:39  For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.
Act 2:40  And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation.

(NOW)2Ti 4:1  I charge thee therefore before God, and the Lord Jesus Christ, who shall judge the quick and the dead at his appearing and his kingdom;
2Ti 4:2  Preach the word; be instant in season, out of season; reprove, rebuke, exhort with all longsuffering and doctrine.
2Ti 4:3  For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears;
2Ti 4:4  And they shall turn away their ears from the truth, and shall be turned unto fables.
2Ti 4:5  But watch thou in all things, endure afflictions, do the work of an evangelist, make full proof of thy ministry.
2Ti 4:6  For I am now ready to be offered, and the time of my departure is at hand.
2Ti 4:7  I have fought a good fight, I have finished my course, I have kept the faith:
2Ti 4:8  Henceforth there is laid up for me a crown of righteousness, which the Lord, the righteous judge, shall give me at that day: and not to me only, but unto all them also that love his appearing.

(FUTURE) Rev 11:15  And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
Rev 11:16  And the four and twenty elders, which sat before God on their seats, fell upon their faces, and worshipped God,
Rev 11:17  Saying, We give thee thanks, O Lord God Almighty, which art, and wast, and art to come; because thou hast taken to thee thy great power, and hast reigned.
Rev 11:18  And the nations were angry, and thy wrath is come, and the time of the dead, that they should be judged, and that thou shouldest give reward unto thy servants the prophets, and to the saints, and them that fear thy name, small and great; and shouldest destroy them which destroy the earth.
Rev 11:19  And the temple of God was opened in heaven, and there was seen in his temple the ark of his testament: and there were lightnings, and voices, and thunderings, and an earthquake, and great hail.